CVE-2020-4071

Timing attack on django-basic-auth-ip-whitelist

Workarounds

Stop using basic authentication and use the IP whitelisting component only. It can be achieved by not setting BASIC_AUTH_LOGIN and BASIC_AUTH_PASSWORD in Django project settings.

References

• Django mailing list discussion

For more information

If you have any questions or comments about this advisory:

• Open an issue at https://github.com/tm-kn/django-basic-auth-ip-whitelist/issues
• Email us at the email specified on the security policy.

Acknowledgements

Thanks to Thibaud Colas for reporting this.

Potential timing attack exists on websites where the basic authentication is used or configured, i.e. BASIC_AUTH_LOGIN and BASIC_AUTH_PASSWORD is set. Currently the string comparison between configured credentials and the ones provided by users is performed through a character-by-character string comparison. This enables a possibility that attacker may time the time it takes the server to validate different usernames and password, and use this knowledge to work out the valid credentials. This attack is understood not to be realistic over the Internet. However, it may be achieved from within local networks where the website is hosted, e.g. from inside a data centre where a website's server is located.

Sites protected by IP address whitelisting only are unaffected by this vulnerability.

CVE-2020-4071 has a CVSS score of 2.2 (Medium). The vector is requires physical access, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.3.4); upgrading removes the vulnerable code path.

Kodem intelligence

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This vulnerability has been fixed on version 0.3.4 of django-basic-auth-ip-whitelist. Update to version 0.3.4 as soon as possible and change basic authentication username and password configured on a Django project using this package.

1. What is CVE-2020-4071? CVE-2020-4071 is a medium-severity security vulnerability in django-basic-auth-ip-whitelist (pip), affecting versions < 0.3.4. It is fixed in 0.3.4.
2. How severe is CVE-2020-4071? CVE-2020-4071 has a CVSS score of 2.2 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of django-basic-auth-ip-whitelist are affected by CVE-2020-4071? django-basic-auth-ip-whitelist (pip) versions < 0.3.4 is affected.
4. Is there a fix for CVE-2020-4071? Yes. CVE-2020-4071 is fixed in 0.3.4. Upgrade to this version or later.
5. Is CVE-2020-4071 exploitable, and should I be worried? Whether CVE-2020-4071 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2020-4071 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2020-4071? Upgrade django-basic-auth-ip-whitelist to 0.3.4 or later.